Canon 1242B002 EF-S 17-55mm f/2.8 IS USM camera lens

EF-S 17-55mm f/2.8 IS USM for APS-C

Canon's EF-S 17-55mm f/2.8 IS USM is a constant-aperture standard zoom built for APS-C DSLRs. It covers a 27-88mm equivalent range with a maximum aperture of f/2.8 throughout. The lens uses 19 elements in 12 groups, including UD and aspherical elements. Optical image stabilization and an ultrasonic autofocus motor with manual override are included.

Step up from variable-aperture kit zooms

This lens replaces slower variable-aperture zooms that drop to f/5.6 at the long end. The constant f/2.8 aperture maintains brightness across the 17-55mm range, making the jump worthwhile for handheld photography in low-light situations where shutter speed must stay high. It also provides shallower depth of field than typical kit lenses at equivalent focal lengths.

Constant f/2.8 holds exposure while shooting

Under sustained use, the fixed f/2.8 aperture keeps exposure consistent while zooming, avoiding the brightness loss common with variable-aperture designs. The ultrasonic motor drives autofocus quickly and quietly during extended sessions. Optical stabilization assists steady framing at the 55mm end, where camera shake is most noticeable at the 1.15ft minimum focus distance.